Folding knife and tool combinations such as the socalled Swiss Army knife have been known for many years, and so have switch-blade knives and the like.
However, most combination knives suffer from one or more defects to the extent that none has become the standard of commerce for the purposes intended. The defects may include awkwardness or instability in deployment and/or in use, weakness, lack of versatility, expense, undue size and/or weight, corrosion susceptibility, slipperyness in grip, impositiveness in action.